Cleaned my carbs, bike won't run right. Pls help

[Muscle racer]

Hey guys.

So I finally got the courage to take my carbs apart, and clean it. Took me months to actually go ahead with it.
My bike is how I get to work everyday, so I was nervous I wouldn't put it back together right.

I looked up hundreds of links and videos.

I got the gaskets I needed and the carb cleaner.

Took it all apart. It was definitely dirty, but not as bad as I thought.  Removed all the jets. Some where plugged up, and I cleaned them.

I let it all dry over night and put it back together the next day.

Putting it back on the bike was a pain, bc the rubber boots weren't fitting right and the air box wasnt lining up.
I finally got it, and put some gas on it. Took a few mins to actually spark.

Here's my question. I know it needs to be adjusted and tuned right.  it needs choke to get started.
When idling, it dies as soon as I give it some gas.
There's a little bit of gas dripping from the float bowl overflow tubes.

I was so happy that it actually turned on. I can't wait to get it tuned and see how it runs with clean carbs.

Any insight will make my day.

Thanks gentlemen

[shultz_1978]

Hi
  Did you blow out all the jet and passages in the carbs?

  Did You bench synce them?

  You will be come a pro at taking these carbs off and on.

[Muscle racer]

I didn't use air. I find a thin nail. I couldn't see light threw them before, I can now.

I have a the 4 gauge tool to synch the carbs. Haven't done it yet. Wanted to make sure the bike would run first.

I turned the fuel mixture screw 1 1/4 turns.

I didn't do anything as far as adjusting the float heights. Seemed to be fine in the first place.

[Piute]

shultz_1978 wrote

Hi
  Did you blow out all the jet and passages in the carbs?

  Did You bench synce them?

  You will be come a pro at taking these carbs off and on.

     Did you blow out all the jet and passages in the carbs?
                AFTER THEY DRY or been setting?

     Did You bench sync them?
                SET ALL MINE by using allen wrench
 
    You will be come a pro at taking these carbs off and on.
               AFTER 3rd TIME and running right was just a pain not a challenge(best with 2 people)

[Muscle racer]

I blew thru the jets after I unplugged them, but not the passages.

I let the carb body sit in carb cleaner for a few hrs. Then rinsed and let air dry.

[Lucky 1]

What year was the mototcycle??

Have to know before answering any detailed questions..

[shultz_1978]

I believe it is a 78 k he has.

[Muscle racer]

Sorry. It's a 78 k. I just looked at the service manual, and when I pulled the main jet, the small needle jet never came out. And there's a needle in the hole. The manual says the main jet comes apart from the jet needle holder, but it's connect.

The manual says not to pull out the slow jet bc it's a press fit, but I used pliers and pulled them, and it was clogged.

[Muscle racer]

When it's idling, it dies when I turn the throttle a little bit. I thought it might have been a rich/lean mixture problem, but I turn the pilot screw 1 1/4 turns, like the manual says

[Muscle racer]

I'm synching the carbs today after the Falcons game, we'll see if that fix it.

RISE UP!!!

[Lucky 1]

Does your 1978 CB750 have the stock exhausts and the stock air filters?

If not .....it will NEVER run right until it is rejetted.
Also the accelerator pump system MUST be working.

To check it  get a bright led flashlight and when it is NOT running but has the gas turned on look inside the intake at the carb and turn the throttle a couple of times. You should see gas squirt from the brass nozzle sticking up in the throat of the carb.
If you see no gas squirt then you will have to check the accelerator pump and get it working.
IT has two check valves and the one in the bottom plate of the accelerator pump has to be working or the whole system will not work.

[Muscle racer]

The air box is stock and cleaned. The exhaust is not stocked. Everything was working before I cleaned the carbs. There was just a very small leak, and they looked dirty and gummed up on the outside.

I did see gas squirt out when I turned the throttle

[shultz_1978]

It is ok to pull the low jets out just be easy with them not to bend them. Make sure the little holes a round the out side of them are also clean. If it run befor you can get it to run again.

Did you take them completly apart when you cleaned them? Top off, sides out everthing?

If you had the carbs all the way apart you should bench synce when you are putting them back together.

Good luck.

[seestheday]

I'm not an expert on SOHC carbs, but did you say you used a thin nail to clear the passages?  Reason I ask is that most passages are way too small for an nail to clear.  You need to use a high e string from a guitar.  Like a .009 or .010.

If you pushed a nail through the jets then they might have been enlarged, which will cause you all sorts of issues.

[Muscle racer]

Yea the nail was big. Then I tried a very thin copper wire I stripped from another wire. It worked.

Yea, I keep hearing about a bench synch but I don't know how to do that. It was a pain getting the carbs and the airbox to get back on, but ill take them off to get it going again.

I read that it's good to keep all the jets together but seperate from the other jets. I just put everything together and cleaned it. Everything looked exactly the same, so I didn't think it mattered

[rrgunslinger]

You don't have to remove the carbs to bench sync them. You will need to remove the air filter and box so you can access the crabs.  There are instructions on this site on how to do it, also no the net.

[seestheday]

Wait, all the jets? Did you mix primary and secondary?   Do they look the same on these carbs? On the dohc carbs it is possible to put primary jets where secondary jets go and vice versa.  If you mix them up the sizes are wildly different, and your bike won't run right. 

Sent from my BlackBerry device

From: Muscle racer [via Honda CB750'S]

Sent: Sunday, January 20, 2013 6:54 PM

To: seestheday

Subject: Re: Cleaned my carbs, bike won't run right. Pls help

Yea the nail was big. Then I tried a very thin copper wire I stripped from another wire. It worked.

Yea, I keep hearing about a bench synch but I don't know how to do that. It was a pain getting the carbs and the airbox to get back on, but ill take them off to get it going again.

I read that it's good to keep all the jets together but seperate from the other jets. I just put everything together and cleaned it. Everything looked exactly the same, so I didn't think it mattered

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[robs750]

shultz_1978 wrote

Did you blow out all the jet and passages in the carbs?

I think this is very important!

[SoonerRon]

I always soak the carb bodies in pinesol overnight, then rinse with water and blow out every opening with compresses air. Pinesol does a fantastic job of removing varnish and cheap too. I follow that up with brake cleaner through everything and blow that out. I also probe each passage, especially the idle circuit, with an high E guitar string ~ 0.0012". I think that's critical for good idling.

[Muscle racer]

I found out how to bench synch the carbs.
The carbs in the video had the butterfly flaps closed, but mine stay open.

How do I change that?